Process of treating cast-iron.



J. E. JOHNSON, JR.

PROCESS OF TREATING CAST IRON.

APPLICATION FILED 0:0. 8. 1913.

1,150,201. atentd Aug. 17, 1915.

Attest: nvento 2210 11 by .f Lm

M W A S.

UNITED STATES PATENT OFFICE.

JOSEPH E. JOHNSON, JR., NEW YORK, N. Y.

PROCESS OF TREATING- CAST-IRON.

Specification of Letters Patent.

Patented Aug. 17, 19115.

Application filed December 8, 1913. Serial No. 805,251.

To all whom it may concern:

Be it known that I, Josnrn: E. JOHNSON, J12, a citizen of the UnitedStates, residing at New York, in the county of New York and State of NewYork, have invented certain new and useful Improvements in Processes ofTreating Cast-Iron, of which the in, the oxygen tending to cause thecarbon to take the combined rather than the graphitic condition, andcausing the graphite formed when the metal cools, to take the form ofnodules rather than that of flakes.

For certain purposes it is very desirable that the iron be of thisstructure, but for other purposes for which cast iron is used, suchstructure of the iron is objectionable and therefore it is desirable toremove the oxygen so that the iron will not only be free from chillingproperties but the graphite will take the form of flakes, these twoconditions conducing to softness of the iron.

In the'removal. of the oxygen, which is the aim of my invention, I takeadvantage of the chemical reactions which will occur between oxygen andother constituent elements of the iron, such as silicon and carbon,

under temperature conditions considerably higher than the temperature atwhich the iron comes from the furnace, and while subjecting a bath ofthe molten iron to such temperature conditions, I, in accordance with myinvention, maintain such a condition above the surface of the bath, thatoxygen will be prevented from entering the bath at this point. As aresult of this proceeding, the oxygen will be effectually removed,leaving the iron free from chilling qualities and the graphite in flakyform.

In the accompanying drawings, I have shown an electric furnace of theinduction .type which I find preferable for carrying my process intopractice.

In the practice of the process I heat a bath A of cast iron 1 anelectric furnace B constructed with a chamber or space b above thesurface of the bath the purpose of which will presently appear. Thedegree of heat given the bath is such as to promote reactions betweenthe oxygen and other constituent elements of the iron particularlysilicon and carbon, the oxygen combining with the silicon and formingsilica which will float on the surface of the bath,

and combining also with the carbon of the bath, thereby forming CO gaswhich will leave the bath in the form of bubbles. The temperature whichI find necessary to promote these reactions, is considerably above thatof the iron when it is tapped from the coke furnace, and should be ashigh as 3000 F. or thereabout. During the heating of the bath and whilethe above mentioned reactions are taking place, I maintain above thesurface of the bath, such a condition that oxygen will be prevented fromentering the metal from the outside. Preferably this condition isbrought about by giving the atmosphere above the bath a reducingquality, by injecting into the chamber 6, any desired quantity of CO gas,even as high as 100% of the same. O'r hydrogen gas may be employed forthis purpose, or any of the many hydrocarbon gases. gas may be sointroduced into the chamber b, as to force out the atmospheric air andproducts of the reactions taking place in the bath, the efiect of whichwill be to main tain above the surface of the bath, a condition ofatmosphere which will prevent the entrance of oxygen into the bath.

By the employment of an electric furnace for heating the bath, thedegree of heat ob- Such tainable is under absolute control, and does ingin the removal of the oxygen to the final point or externally. W'hilesuchconditions may be brought about as above stated by inof such baths,the size of the electrodesw ould be unduly large, and therefore suchfurnace would not, be as suitable as that shown.- It

will be understood therefore that my improved process is not limited inits practice to the particular type of furnace shown, but

- may be carried into effect by any means by which the results describedabove are brought about.

Having thus described my invention what I claim is:

1. The process of removing oxygen from cast iron, which consists inheating a bath of said iron to a temperature high enough to promotereaction between the oxygen and other constituents of the bath, whilemaintaining a condition above the bath which will prevent the entranceof oxygen therein.

2. The process of removing'oxygen from cast iron, which consists inheating a bath of said iron in the presence of a reducing atmosphere toa temperature high enough to promote reaction between the oxygen andother constituents of the bath.

v 3. The process of removing oxygen from cast iron, which consists inheating a bath of said iron to a temperature above that at which themetal comes from the furnace, uch temperature being high enoughtopromote reaction between the oxygen and other constituents of the bath,while maintaining Copies of this patent may be obtained for a conditionabove the bath which will pre vent the entrance of oxygen therein.

4. The method of removing oxygen from cast iron, which consists inheating a bath of said iron in an electric furnace to a term peraturewhich will promote reaction between the oxygen and other constituents ofthe bath, said heating being carried on under conditions which willprevent the entrance of oxygen into the bath.

5. The method of removing oxygen from cast iron, which consists inheating a bath of said iron in an electric furnace to a temperature wellabove that at which the iron .comes from the coke furnace, suchtemperature being high enough to promote reaction between the oxygen andother constituents of the bath, and maintaining over said bath anatmosphere of a reducing nature to prevent the entrance of oxygen intothe bath.

6. The method of removing oxygen from cast iron, which consists inheating a bath of said iron in an electric furnace to a temperature wellabove that at which the iron comes from the coke furnace suchtemperature being high enoughcto promote reaction between the oxygen andother constituents of the bath, whilemaintaining such a condition abovethe bath that oxygen will be prevented from entering therein.

7. The method of removing oxygen from cast iron, which'consists' inheating a bath of said iron to a temperature sufficient to promotereactions between the oxygen, silicon and carbon of the bath, whilemaintaining such a condition above the bath that the entrance of. oxygentherein will be prevented.

In testimony whereof I have affixed my signature in presence .of twowitnesses.

v JOSEPH E. JOHNSON, JR J Witnesses:

. WM. J. DOLAN, WV. R. K NNEDY.

fivecents each, by addressing the "Commissioner of Patent. Washington,D. G.

